Staged method to detect brake fail conditions in brake control systems

Abstract

A system for two-stage determination of a brakefail of an aircraft brake system includes an aircraft brake. The aircraft brake is configured to receive a current command value, convert the current command value to a braking pressure and output a detected pressure value corresponding to the braking pressure. The system also includes a brake control unit (BCU) configured to determine a pressure command value, convert the pressure command value to the current command value and to determine whether a brakefail event has occurred based on the pressure command value, the current command value and the detected pressure value.

What is claimed is: 
     
       1. A system for two-stage determination of a brakefail of an aircraft brake system comprising:
 an aircraft brake configured to receive a current command value, convert the current command value to a braking pressure, and output a detected pressure value corresponding to the braking pressure; and 
 a brake control unit (BCU) configured to:
 determine a pressure command value, 
 convert the pressure command value to the current command value, 
 determine whether a brakefail event has occurred based on the pressure command value, the current command value, and the detected pressure value, and 
 determine that the brakefail event has occurred in response to determining that the current command value is within a predetermined current tolerance of at least one of a maximum current value or a minimum current value. 
 
 
     
     
       2. The system of  claim 1 , wherein the BCU is further configured to determine that the brakefail event has occurred in response to determining that the detected pressure value is greater than or less than the pressure command value by at least a predetermined pressure tolerance. 
     
     
       3. The system of  claim 2 , wherein the BCU is further configured to determine that the brakefail event has occurred in response to determining that the detected pressure value is greater than or less than the pressure command value by at least the predetermined pressure tolerance or that the current command value is within the predetermined current tolerance of the maximum current value or the minimum current value for a predetermined period of time. 
     
     
       4. The system of  claim 3 , wherein the BCU is configured to determine that the brakefail event has stopped occurring in response to determining that the detected pressure value is within the predetermined pressure tolerance of the pressure command value and that the current command value is less than the maximum current value minus the predetermined current tolerance and is greater than a sum of the minimum current value and the predetermined current tolerance for the predetermined period of time. 
     
     
       5. The system of  claim 1 , wherein the pressure command value is received from a brake control executive unit and is determined based on a pilot desired pressure value and a desired pressure command value. 
     
     
       6. The system of  claim 1 , wherein the current command value is determined using a feedback loop based on the pressure command value and the detected pressure value when the brakefail event has not occurred. 
     
     
       7. The system of  claim 6 , wherein the current command value is determined using an open loop based on the pressure command value when the brakefail event has occurred. 
     
     
       8. A system for two-stage determination of a brakefail of an aircraft brake system comprising:
 an aircraft brake having a plurality of electronic actuators each configured to receive a current command value, to convert the current command value into a force, and to output a detected or calculated force value; and 
 a brake control unit (BCU) configured to:
 determine a force command value, 
 convert the force command value to the current command value, 
 determine whether a brakefail event has occurred based on the force command value, the current command value, and the detected or calculated force value from each of the plurality of electronic actuators, 
 determine that an actuator fail event has occurred for an electronic actuator of the plurality of electronic actuators in response to determining that at least one of the detected or calculated force value for the electronic actuator is at least one of greater than or less than the force command value by at least a predetermined force tolerance, and 
 determine that the brakefail event has occurred in response to determining that the actuator fail event has occurred for a predetermined quantity of the plurality of electronic actuators. 
 
 
     
     
       9. The system of  claim 8 , wherein the BCU is further configured to determine that the actuator fail event has occurred for the electronic actuator in response to determining that the current command value is within a predetermined current tolerance of a maximum current value or a minimum current value for the electronic actuator. 
     
     
       10. The system of  claim 9 , wherein the BCU is further configured to determine that the actuator fail event has occurred in response to determining that the detected or calculated force value is greater than or less than the force command value by at least the predetermined force tolerance or that the current command value is within the predetermined current tolerance of the maximum current value or the minimum current value for a predetermined period of time. 
     
     
       11. The system of  claim 10 , wherein the BCU is configured to determine that the actuator fail event has stopped occurring in response to determining that the detected or calculated force value is within the predetermined force tolerance of the force command value and that the current command value is less than the maximum current value minus the predetermined current tolerance and is greater than a sum of the minimum current value and the predetermined current tolerance for the predetermined period of time. 
     
     
       12. The system of  claim 11 , wherein the BCU is configured to determine that the brakefail event has stopped occurring in response to determining that the actuator fail event is occurring for less than the predetermined number of the plurality of electronic actuators. 
     
     
       13. A method for two-stage determination of a brakefail of an aircraft brake system comprising:
 determining, by a brake control unit (BCU), a pressure command value or a force command value; 
 converting, by the BCU, the pressure command value or the force command value to a current command value; 
 receiving, by the BCU, a detected pressure value or a detected or calculated force value; 
 determining, by the BCU, whether a brakefail event has occurred based on the pressure command value or the force command value, the current command value, and the detected pressure value or the detected or calculated force value; 
 determining, by the BCU, that the brakefail event has occurred in response to determining that at least one of the detected pressure value is greater than or less than the pressure command value by at least a predetermined pressure tolerance or the current command value is within a predetermined current tolerance of a maximum current value or a minimum current value for a predetermined period of time; and 
 determining, by the BCU, that the brakefail event has stopped occurring in response to determining that the detected pressure value is within the predetermined pressure tolerance of the pressure command value and that the current command value is less than the maximum current value minus the predetermined current tolerance and is greater than a sum of the minimum current value and the predetermined current tolerance for the predetermined period of time. 
 
     
     
       14. The method of  claim 13 , further comprising determining, by the BCU, that an actuator fail event has occurred for an electronic actuator of a plurality of electronic actuators of an aircraft brake in response to determining that at least one of the detected or calculated force value for the electronic actuator is greater than or less than the force command value by at least a predetermined force tolerance or the current command value is within a predetermined current tolerance of a maximum current value or a minimum current value for the electronic actuator for a predetermined period of time. 
     
     
       15. The method of  claim 14 , further comprising determining, by the BCU, that the brakefail event has occurred in response to determining that the actuator fail event has occurred for a predetermined number of the plurality of electronic actuators.